1. Technical Field
The present disclosure relates to an optical lens, a lens array, and a lighting apparatus.
2. Description of the Related Art
For example, lighting apparatuses disposed outside, such as road lights, street lights, tunnel lights, and parking lot lights, are often installed on lighting poles, for instance. The place where a lighting pole is installed is at a location where the pole does not block the paths of persons, vehicles, and so on. For example, if a lighting pole is installed on the roadside, an illumination target that is to be illuminated by a lighting apparatus is at a location shifted forward (toward the road) from the place where the lighting apparatus is installed. If a lighting apparatus emits light rearward of the lighting apparatus, this causes glare, for example. Thus, there is a demand for preventing a lighting apparatus from emitting light rearward of the lighting apparatus. To meet this demand, Japanese Unexamined Patent Application Publication No. 2014-191336 (Patent Literature 1) discloses a technique of controlling distribution of light from a lighting apparatus, using, for example, an optical lens which covers a light emitting diode (LED) light source.